5.2 Study of Deformations of Epithelial Tissues Using the …
379
(“Micrat-N”) was processed in a standard developer PMT. The energy of the illuminating laser pulse was usually selected in such a way that the specklograms were
overexposed. They were bleached in a number of experiments. Nonlinear registration
of specklograms enlarges the cone of the diffracted light during further reconstruction
and leads to the appearance of a great number of interference fringes and increase
of accuracy of deformations.
The posterior processing of speckle-photographs was made in the following way:
A 24 × 35 mm
2 slide was scanned with a thin laser beam with a diameter of about
2 mm. A long-focal optical system f = 300 mm was placed behind it. The system
conducts Fourier transformation of the light diffracted on the lighted area of the
specklogram. Interference fringes were formed in the focal plane. Their direction
and period reflect the shift of the surface under study, and
T =
λd
m
(5.3)
where is the shift; m is the magnification of the optical system used during
specklogram recording.
The focal distance f determines the scale of fringes. The characteristics of the
interference pattern were measured on a special display that gives the possibility to
filter that part of the light, which passed through the slide without diffraction, and
has the possibility of angular attitude (with measuring the angle) and the measuring
scale for determination of the fringe period.
Some typical speckle-interferograms are presented in Fig. 5.4a, b. They were
made during filtering of non-diffracted light and reflecting deformation of separate
areas of webbing. Also, a definite deformation field of the whole leg in 20 ms after
the beginning of irritation is presented in the same figure.
Contractions of the elastic living tissue are accompanied by deformations and
have considerable heterogeneity.
The diameter of the scanning beam had to be varied from 3 to 1 mm using a
diaphragm for determining such deformations as, for example, in the right upper part
of the figure in order to increase the contrast of bands and to change the resolution of
the method. Deformations of the epithelial tissue during contractions were studied
as a result of double-pulsed speckle-photography method (λ = 694.3 nm). Optimal
conditions were determined for obtaining a speckle-photography of living tissue.
The setup made on the basis of a pulse ruby laser gave the possibility to register the
shift field on the area of about 6 cm
2 with spatial resolution of 2–4 mm
2 .
A homogeneous deformation field of contracting epithelial tissue was investigated
within the interval from 10 to 50 ms. After the beginning of contractions, vector
diagrams of shifts were built, the range of which was from 40 to 205 μm.
Among the advantages of the method, the following ones should be mentioned:
contactlessness, simple realization and equipment, and high accuracy (ranges of the
measured fringe from dozens of micrometers to millimeters).
A disadvantage is a two-stage process of deformation determination—filming of
specklograms and their posterior processing. Besides, the value of longitudinal shifts,
379
(“Micrat-N”) was processed in a standard developer PMT. The energy of the illuminating laser pulse was usually selected in such a way that the specklograms were
overexposed. They were bleached in a number of experiments. Nonlinear registration
of specklograms enlarges the cone of the diffracted light during further reconstruction
and leads to the appearance of a great number of interference fringes and increase
of accuracy of deformations.
The posterior processing of speckle-photographs was made in the following way:
A 24 × 35 mm
2 slide was scanned with a thin laser beam with a diameter of about
2 mm. A long-focal optical system f = 300 mm was placed behind it. The system
conducts Fourier transformation of the light diffracted on the lighted area of the
specklogram. Interference fringes were formed in the focal plane. Their direction
and period reflect the shift of the surface under study, and
T =
λd
m
(5.3)
where is the shift; m is the magnification of the optical system used during
specklogram recording.
The focal distance f determines the scale of fringes. The characteristics of the
interference pattern were measured on a special display that gives the possibility to
filter that part of the light, which passed through the slide without diffraction, and
has the possibility of angular attitude (with measuring the angle) and the measuring
scale for determination of the fringe period.
Some typical speckle-interferograms are presented in Fig. 5.4a, b. They were
made during filtering of non-diffracted light and reflecting deformation of separate
areas of webbing. Also, a definite deformation field of the whole leg in 20 ms after
the beginning of irritation is presented in the same figure.
Contractions of the elastic living tissue are accompanied by deformations and
have considerable heterogeneity.
The diameter of the scanning beam had to be varied from 3 to 1 mm using a
diaphragm for determining such deformations as, for example, in the right upper part
of the figure in order to increase the contrast of bands and to change the resolution of
the method. Deformations of the epithelial tissue during contractions were studied
as a result of double-pulsed speckle-photography method (λ = 694.3 nm). Optimal
conditions were determined for obtaining a speckle-photography of living tissue.
The setup made on the basis of a pulse ruby laser gave the possibility to register the
shift field on the area of about 6 cm
2 with spatial resolution of 2–4 mm
2 .
A homogeneous deformation field of contracting epithelial tissue was investigated
within the interval from 10 to 50 ms. After the beginning of contractions, vector
diagrams of shifts were built, the range of which was from 40 to 205 μm.
Among the advantages of the method, the following ones should be mentioned:
contactlessness, simple realization and equipment, and high accuracy (ranges of the
measured fringe from dozens of micrometers to millimeters).
A disadvantage is a two-stage process of deformation determination—filming of
specklograms and their posterior processing. Besides, the value of longitudinal shifts,